Alkylperoxy Radicals RO

The reaction involves abstraction of a hydrogen atom to form HC1  

As already seen, the reactions of OH, N03, and Cl with alkanes generate alkyl radicals. We shall see in the subsequent sections of this chapter that the production of alkyl radicals of various types is a general characteristic of organic oxidations. Here we will trace the atmospheric fates of typical alkyl radicals formed in OH, NO-, and Cl atom oxidations of alkanes. However, the principles are general and can be applied to those formed by the reactions of other organics such as alkenes as well. 

The only fate of alkyl radicals in air is reaction with 02  

For the case where R is a methyl group, the reaction is in the falloff region at 1 atm, and for C2H5, it is close to the high-pressure limit. For C3H7 and above, a value for the effective second-order rate constant, k.r, of (0.8-2) X 10 11 cnr1 molecule 1 s 1 means that the lifetime of an alkyl radical at 1 atm in air is 10 ns. 

Alkylperoxy radicals (R02) in the atmosphere react primarily with NO, H02, and other R02. Reaction with the nitrate radical, N03, at night, has been recently recognized as being important as well. A less important reaction is that with N02. There are two excellent reviews of R02 chemistry by Lightfoot et al. (1992) and Wallington et al. (1992), including the thermochemistry, spectroscopy, kinetics, and mechanisms. The reader should consult these for references to the original work in this area. 

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Alkylperoxy radicals RO are key intermediates (chain carriers) from which the primary product alkyl hydroperoxide, 2 derived. 

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